Annotations
Urography
in acute
renal failure
In 1963, Schwartz, Hurwit, and Ettinger’ showed that excretion urography could be used in patients with renal failure to define the shape and size of the kidneys and to diagnose or exclude extrarenal obstruction. Since then, high-dose urography has become widely accepted as a valuable part of the routine investigation of patients with renal failure (reviewed in 1971).’ However severe the renal failure, opacification of the renal substance is almost always sufficient to define the renal outlines and there is almost always enough visualization of the pelvicalyceal system to define or exclude obstruction. This is true even in patients presenting acutely with oliguria or anuria.“-i A recent report6 suggests that urography may prove to be of further value in patients with acute renal failure by helping to establish the diagnosis of acute tubular necrosis (ATN). The report describes the appearances during excretion urography in 32 patients with nonobstructive acute renal failure, twelve of whom were anuric and ten oliguric. The study was mainly concerned with the degree of opacification of the renal substance by contrast medium during the course of excretion urography (the nephrographic pattern).’ In normal subjects, the nephrogram is most dense at the end of injection, fading quickly as the blood level falls. In each of twelve patients with uncomplicated ATN there was an obvious immediate nephrogram which, instead of fading, persisted for up to 24 hours or more. This observation confirms, in a clinical setting, reports of the same abnormal nephrographic pattern in rata with acute renal failure induced by vascular clamping or mercury poisoning.“. y The same nephrographic pattern was also observed in three out of five patients in whom oliguric renal failure was due to acute suppurative pyelonephritis. It has not been reported in any other conditions. The remaining patients showed differing abnormalities of the nephrographic pattern, but because of the small number of patients it was not possible to assess the significance of the appearances except in as much as they excluded the diagnosis of uncomplicated ATN. Two patients were of particular interest since the clinical diagnosis was one of uncomplicated ATN. Instead of the expected, immediate, obvious persistent nephrogram both showed only a faint nephrogram initially which gradually became more dense over the next 24 hours. In both patients, the ATN was complicated by antecedent kidney disease, in one case renal amyloid, in the other case chronic glomerulonephritis. If these abnormalities of the nephrographic pattern are confirmed, excretion urography will clearly be of value in the management of patients with acute renal failure. In this condition, both short-term and long-term treatment depend on whether the lesion is potentially reversible, e.g., uncomplicated ATN, or irreversible, e.g., cortical necrosis, fulminating proliferative glomerulonephritis, etc. In many patients the clinical picture may be so typical that no further investigation is required. In others there may be doubt. Renal biopsy can provide a histologic diagnosis in many cases, but should not be undertaken lightly because of the increased hazard of hemor-
124
rhage in such patients Furthermore, biopsy may not be conclusive in patients with ATN and a retrospective diagnosis may have to wait upon recovery after weeks of dialysis. If urography can establish a diagnosis of uncomplicated ATN in the frrst few days it will remove uncertainty from the management of this type of patient. One word of caution. Urography was previously considered dangerous in patients with renal failure because it appeared, occasionally, to be responsible for severe deterioration in renal function. More recent studie+ i. 6. I0 have suggested that this is not so provided the patient is not clinically dehydrated at the time of examination and fluids are not restricted. This is particularly important in patients with acute renal failure. In practice it means that prerenal failure must be excluded before urography. It must also be emphasized that most patients with acute renal failure are seriously ill at the time of presentation and many will require immediate dialysis. If good results are to be obtained and if the patient is not to be put at risk, excretion urography should only be undertaken when there is the closest cooperation between radiologist and clinician.
W. R. Cattell, M.D. I. Kelsey Fry, M.D. Department of Nephrology St. Bartholomew’s Hospital West Smithfield London EClA 7 BE, England REFERENCES 1.
2. 3.
4.
5.
6.
7.
a.
9.
10.
Schwartz, W. B., Hurwit, A., and Ettinger, A.: Intravenous urography in the patient with renal insufficiency, N. Engl. J. Med. 269:277, 1963. Fry, I. K., and Cattell, W. R.: Radiology in the diagnosis of renal failure, Br. Med. Bull. 27:148, 1971. Mahaffy, R. G., Matheson, N. A., and Caridis, D. T.: Infusion pyelography in acute renal failure, Clin. Radiol. 20:320, 1969. Brown, C. B., Glancy, J. J., Fry, I. K., and Cattell, W. R.: High-dose excretion urography in oliguric renal failure, Lancet 2:952, 1970. Meadows, S. R., Cameron, J. S., Ogg, C. S., and Saxton, H. M.: Children referred for acute dialysis, Arch. Dis. Child. 46:221, 1971. Cattell, W. R., McIntosh, C. S., Moseley, I. F., and Fry, I. K.: Excretion urography in acute renal failure, Br. Med. J. 2575, 1973. Fry, I. K., and Cattell, W. R.: The nephrographic pattern during excretion urography, Br. Med. Bull. 26:227, 1972. Chamberlain, M. J., and Sherwood, T.: Intravenous urography in experimental acute renal failure in the rat, Nephron 4:65, 1967. Risdon, R. A., Berry, C. L., and Chrispin, A. R.: Urographic changes in acute papillary necrosis in the rat, Br. Mad. J. 3:263, 1970. Davidson, A. J., Becker, J., Rothfield, N., Unger, G., and Ploch, D. R.: An evaluation of the effect of high-dose urography on previously impaired renal and hepatic function in man, Radiology 97:249, 1970.
July, 1975, Vol. 90, No. 1
Urography
in acute
renal failure
In 1963, Schwartz, Hurwit, and Ettinger’ showed that excretion urography could be used in patients with renal failure to define the shape and size of the kidneys and to diagnose or exclude extrarenal obstruction. Since then, high-dose urography has become widely accepted as a valuable part of the routine investigation of patients with renal failure (reviewed in 1971).’ However severe the renal failure, opacification of the renal substance is almost always sufficient to define the renal outlines and there is almost always enough visualization of the pelvicalyceal system to define or exclude obstruction. This is true even in patients presenting acutely with oliguria or anuria.“-i A recent report6 suggests that urography may prove to be of further value in patients with acute renal failure by helping to establish the diagnosis of acute tubular necrosis (ATN). The report describes the appearances during excretion urography in 32 patients with nonobstructive acute renal failure, twelve of whom were anuric and ten oliguric. The study was mainly concerned with the degree of opacification of the renal substance by contrast medium during the course of excretion urography (the nephrographic pattern).’ In normal subjects, the nephrogram is most dense at the end of injection, fading quickly as the blood level falls. In each of twelve patients with uncomplicated ATN there was an obvious immediate nephrogram which, instead of fading, persisted for up to 24 hours or more. This observation confirms, in a clinical setting, reports of the same abnormal nephrographic pattern in rata with acute renal failure induced by vascular clamping or mercury poisoning.“. y The same nephrographic pattern was also observed in three out of five patients in whom oliguric renal failure was due to acute suppurative pyelonephritis. It has not been reported in any other conditions. The remaining patients showed differing abnormalities of the nephrographic pattern, but because of the small number of patients it was not possible to assess the significance of the appearances except in as much as they excluded the diagnosis of uncomplicated ATN. Two patients were of particular interest since the clinical diagnosis was one of uncomplicated ATN. Instead of the expected, immediate, obvious persistent nephrogram both showed only a faint nephrogram initially which gradually became more dense over the next 24 hours. In both patients, the ATN was complicated by antecedent kidney disease, in one case renal amyloid, in the other case chronic glomerulonephritis. If these abnormalities of the nephrographic pattern are confirmed, excretion urography will clearly be of value in the management of patients with acute renal failure. In this condition, both short-term and long-term treatment depend on whether the lesion is potentially reversible, e.g., uncomplicated ATN, or irreversible, e.g., cortical necrosis, fulminating proliferative glomerulonephritis, etc. In many patients the clinical picture may be so typical that no further investigation is required. In others there may be doubt. Renal biopsy can provide a histologic diagnosis in many cases, but should not be undertaken lightly because of the increased hazard of hemor-
124
rhage in such patients Furthermore, biopsy may not be conclusive in patients with ATN and a retrospective diagnosis may have to wait upon recovery after weeks of dialysis. If urography can establish a diagnosis of uncomplicated ATN in the frrst few days it will remove uncertainty from the management of this type of patient. One word of caution. Urography was previously considered dangerous in patients with renal failure because it appeared, occasionally, to be responsible for severe deterioration in renal function. More recent studie+ i. 6. I0 have suggested that this is not so provided the patient is not clinically dehydrated at the time of examination and fluids are not restricted. This is particularly important in patients with acute renal failure. In practice it means that prerenal failure must be excluded before urography. It must also be emphasized that most patients with acute renal failure are seriously ill at the time of presentation and many will require immediate dialysis. If good results are to be obtained and if the patient is not to be put at risk, excretion urography should only be undertaken when there is the closest cooperation between radiologist and clinician.
W. R. Cattell, M.D. I. Kelsey Fry, M.D. Department of Nephrology St. Bartholomew’s Hospital West Smithfield London EClA 7 BE, England REFERENCES 1.
2. 3.
4.
5.
6.
7.
a.
9.
10.
Schwartz, W. B., Hurwit, A., and Ettinger, A.: Intravenous urography in the patient with renal insufficiency, N. Engl. J. Med. 269:277, 1963. Fry, I. K., and Cattell, W. R.: Radiology in the diagnosis of renal failure, Br. Med. Bull. 27:148, 1971. Mahaffy, R. G., Matheson, N. A., and Caridis, D. T.: Infusion pyelography in acute renal failure, Clin. Radiol. 20:320, 1969. Brown, C. B., Glancy, J. J., Fry, I. K., and Cattell, W. R.: High-dose excretion urography in oliguric renal failure, Lancet 2:952, 1970. Meadows, S. R., Cameron, J. S., Ogg, C. S., and Saxton, H. M.: Children referred for acute dialysis, Arch. Dis. Child. 46:221, 1971. Cattell, W. R., McIntosh, C. S., Moseley, I. F., and Fry, I. K.: Excretion urography in acute renal failure, Br. Med. J. 2575, 1973. Fry, I. K., and Cattell, W. R.: The nephrographic pattern during excretion urography, Br. Med. Bull. 26:227, 1972. Chamberlain, M. J., and Sherwood, T.: Intravenous urography in experimental acute renal failure in the rat, Nephron 4:65, 1967. Risdon, R. A., Berry, C. L., and Chrispin, A. R.: Urographic changes in acute papillary necrosis in the rat, Br. Mad. J. 3:263, 1970. Davidson, A. J., Becker, J., Rothfield, N., Unger, G., and Ploch, D. R.: An evaluation of the effect of high-dose urography on previously impaired renal and hepatic function in man, Radiology 97:249, 1970.
July, 1975, Vol. 90, No. 1
